7xxx alloy components for defense application with an improved spall resistance

ABSTRACT

The present application relates to armor components made of high strength aluminum, such as 7xxx series aluminum alloys, which may be employed in civil or military ballistic protection systems. It relates more particularly to armor components such as armor hull walls and add-on armor appliques in vehicles.

BACKGROUND Technical Field

The present application relates to armor components made of highstrength aluminum, such as 7xxx series aluminum alloys, which may beemployed in civil or military ballistic protection systems. It relatesmore particularly to armor components such as armor hull walls andadd-on armor appliques in vehicles.

Description of Related Art

Structures and vehicles are increasingly designed to protect theiroccupants from penetration of projectiles. These projectiles aretypically metal, and may strike the structure at high speed, attemptingto perforate the structure, and thereby inflicting damage to theoccupants. The aim of an armor shield is to provide ballistic defeat ofsuch projectiles or fragments.

The demand of ballistic grade aluminum has seen a large increase due tothe ballistic advantages of this low density metal when utilized asprimary armors on vehicles. Aluminum armors are enablers of lightweightshields, which fit with weight requirements of such vehicles.

An armor panel has a front face, exposed to impacts and shocks, and arear face. Upon impact on such armor panel, an armor piercing projectilecan be completely stopped in the panel. However, some fragments may beviolently ejected from the rear face of the panel, towards the vehicleinterior.

To characterize their shield effectiveness, armor panels performancesmust comply with different requirements. Key requirements includesballistic grade aluminum alloy should achieve a high combination ofarmor piercing (AP) resistance, fragment simulated particle (FSP)resistance, as well as spall resistance.

AP resistance means achieving a predetermined armor piercing V50ballistic limit using a piercing projectile, so called AP round. Thischaracterizes the resistance to perforation. FSP resistance meansachieving a predetermined V50 ballistic limit using another kind ofprojectile: FSP projectile, so-called FSP round, which is defined inMIL-DTL-46593B specification. FSP resistance characterizes the abilityto withstand impacts that generate fragmented debris. V50 ballisticlimit, which has a speed dimension, is defined in MIL-STD-662F (1997)standard. The V50 ballistic limits shall be calculated by taking thearithmetic mean of an equal number of the highest partial and the lowestcomplete penetration impact velocities. The specific V50 required at agiven thickness, the amount of individual FSP tests to include in thecalculation of a V50, and other material requirements can vary betweendifferent aluminum alloys. As an example MIL-DTL-46027K enumerates therequirements for 5083, 5456, and 5059 aluminum alloys.

Spall resistance as indicated within MIL-STD-662F (1997) means that,during ballistic tests conducted in accordance with this standard, nosubstantial detachment or delamination of a layer of material occurs inthe area surrounding the location of the impact, either on the front orthe rear surface of the armor. This pass-fail criterion for spalling andthe related high-low impact velocity averaging used in a V50 evaluationfacilitates the testing method but does not allow for further analysisinto the amount of spall damage. Additionally such a testing method canrequire a sizable volume of metal which can hinder the ability to eitherrapidly prototype or sweep through a range of alloy chemistry,transformation routes, tempering options, etc. . . . . Consequently, inthe present application, spall resistance is quantified using a spallresistance score. Spall resistance score is investigated with a FSP testaccording to MIL-STD-662F (1997) standard. Trials are performed using 20mm FSP rounds which comply with MIL-DTL-46593B. The dimensions of theFSP rounds are the following:

-   -   diameter: 20 mm-0.787 inch;    -   length: 23.0 mm-0.9 inch;    -   flat: 9.3 mm-0.366 inch.

The spall resistance score is determined by the following method. Asshown on FIG. 1, on the rear surface, surrounding the site of impact b,is an area of material which was visibly affected by the ballisticstrike and the partial or complete penetration by the FSP round into theplate. The boundary of this affected area is indicated on FIG. 1 withthe dotted line a. Along with any possible exit hole of the FSP round,any material plug and area of any delaminated material is includedwithin the deformed area. The area also includes bulged or fracturedmaterial, which is still connected to the test plate. Radiatingperpendicular from the direction of impact (i.e. along the rear surface)a length c is measured which represents the longest distance from thesite of impact to the edge or boundary of the deformed area. Thismaximum length c is than doubled and from the new value 20 mm issubtracted, which corresponds to the diameter of the FSP round. Theremaining total is divided by 20 mm, so as to get a dimensionlessparameter, so-called Spall Resistance Score. The spall resistance scoreis 0 when only a plug is formed, and no significant lateral material isaffected by the impact. Higher scores represent multiples of theimpacting round diameter. A better score is as low as possible.

Achieving high AP resistance as well as high FSP resistance remainschallenging. Provisional U.S. application 61/948,870, which is herebyincorporated by reference in its entirety, discloses an armor componentproduced from a 7XXX aluminum series alloy, having an improvedcombination of AP resistance and FSP resistance. The aluminum alloysdisclosed therein consists essentially of:

-   -   8.4 wt. %≤Zn≤10.5 wt. %;    -   1.3 wt. %≤Mg≤2 wt. %;    -   1.2 wt. %≤Cu≤2 wt. %;    -   at least one dispersoid forming element, with a total dispersoid        forming element content higher than 0.05 wt. %;    -   the remainder substantially being aluminum, incidental elements        and impurities.

According to U.S. 61/948,870, the armor component is in the form of aplate having a thickness ranging from about 0.5 to about 3 inches; it isaged to achieve high AP and FSP V50 ballistic limits. Namely, the FSPV50 ballistic limit is such that:

V50 (FSP20 mm)>1633T ²−1479T+1290,

where T is the plate thickness (inch) and the unit of V50 is feet/s.“FSP 20 mm” means FSP trials being conducted with 20 mm diameter rounds.

The AP V50 ballistic limit is such that:

V50 (.3 cal AP mm)>−282T ²+1850 T+610,

where T is the plate thickness (inch) and the unit of V50 is feet/s. “.3cal AP V50” means AP trials being conducted with .30 caliber rounds.

The combined targeted ballistic properties can be obtained through amultiple steps aging during the manufacturing process. A typical agingtreatment is about 4-8 hours at about 110° C.-130° C., followed by about12-20 hours at about 140° C.-160° C.

Besides FSP and AP ballistic resistance, a high spall resistance is alsooften required. The present invention provides armor components havinghigh AP and FSP ballistic resistance as well as improved spallresistance.

SUMMARY OF THE INVENTION

7xxx series aluminum alloy armor components produced in accordance withthe present invention exhibit an improved spall resistance. Processingparameters, as well as the alloy composition, are controlled in order toincrease spall resistance, and to have high AP and FSP ballisticresistance.

The composition of the 7xxx series aluminum alloy is preferably selectedin order to comprise Zr as at least one dispersoid forming element, morepreferably Zr from about 0.04 to about 0.15 wt. %, which results in afurther improvement of the performances.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 depicts an embodiment of the method used to determine the spallresistance score according to the present disclosure.

DETAILED DESCRIPTION OF A PREFERRED EMBODIMENT

Unless otherwise stated, all compositional percentages are expressed inweight percent (wt. %), based on the total weight of the alloy. Alloydesignation is in accordance with the regulations of The AluminumAssociation known of those skilled in the art.

As used herein, the expression “up to” when referring to the amount ofan element means that this elemental composition is optional, andincludes a zero amount of this element. When the term “between” appearsin the present application and claims, it is understood that the upperand lower numbers in the range are included. Similarly, “lower than” or“higher than” and such phrases include the numeral in the recited range.

The present invention relates to a method of producing an armorcomponent, comprising:

-   -   a) casting a 7XXX series aluminum alloy to obtain an ingot, said        alloy consisting essentially of        -   8.4 wt. %≤Zn≤10.5 wt. %;        -   1.3 wt. %≤Mg≤2 wt. %;        -   1.2 wt. %≤Cu≤2 wt. %;        -   at least one dispersoid forming elements, with a total            content of dispersoid forming elements of at least 0.04 wt.            %;        -   the remainder substantially including aluminum, incidental            elements, and impurities;    -   b) homogenizing said ingot;    -   c) hot working said homogenized ingot to obtain a plate having a        first thickness T1;    -   d) cold working the plate having the first thickness to obtain a        plate having a second thickness T2, wherein T2=T1−(x₁*T2)/100        and 0.5≤x₁≤15;    -   e) solution heat treating;    -   f) quenching; and    -   g) aging.

The alloy product according to the invention can be prepared using aconventional melting process and by casting into an ingot form. Duringcasting, the below described grain refiners may be added. After scalpingand homogenizing at 460° C.-520° C. during 5-60 hours, the ingot isfurther hot worked, typically hot worked in several steps, to obtain aplate having a first thickness T1. According to an embodiment, hotworking is hot rolling or forging, and more preferably hot rolling.

It has been shown that performing a cold working step prior to solutionheat treatment (SHT), and more specifically between hot working step andsolution heat treatment, resulted in an improvement of the spallresistance. After the cold working step, the cold worked plate has asecond thickness T2, wherein T2=T1−(x₁*T2)/100 and 0.5≤x₁≤15. Accordingto an embodiment, the cold worked plate has a second thickness T2,wherein T2=T1−(x₁*T2)/100 and 2≤x₁≤10, preferably 4≤x₁≤8. According toan embodiment, said cold working step prior to solution heat treatmentis a cold rolling step.

The cold worked plate having a second thickness T2 is then solution heattreated and quenched. In a preferred embodiment, the solution heattreatment is performed between 1 to 5 hours at 460° C.-480° C. andquenched typically to a temperature lower than 95° C.

Optionally, another cold working step is performed after SHT and quenchto obtain a plate having a third thickness T3. This other cold workingstep can be a stretching. Said other cold working step gives rise to aplastic deformation for example up to 3%, typically between 1 and 3%.When no second cold working step is applied, the second thickness T2 isthe final thickness of the armor component. When the method according tothe invention involves two cold working steps, the final thickness isthe third thickness T3 of the plate obtained after the second coldworking step and the final thickness of the armor component is lowerthan the second thickness T2.

According to an embodiment, step g) includes at least a two step aging.Preferably, this two-step aging includes:

-   -   a first aging step of about 4-8 hours, and more preferably of        about 5-7 hours, at about 110° C. to 130° C., and more        preferably at about 115° C. to 125° C.; and    -   a second aging step of about 12-20 hours, and more preferably        about 14-18 hours, at about 130° C. to 180° C. and more        preferably at about 145° C. to 165° C.

According to another embodiment, aging is performed so that the totalequivalent time at 150° C. ranges between about 5 h to about 50 h, andmore preferably from about 10 h to about 40 h. The total equivalent timet(eq) at 150° C. is given by the expression:

${t({eq})} = \frac{\int{e^{\frac{- 15683}{T}}{dt}}}{e^{\frac{- 15683}{T_{ref}}}}$

where:

-   -   T is the instantaneous temperature in Kelvin of treatment;    -   t denotes the time, including heating and cooling steps;    -   T_(ref) is a reference temperature, whose value is 423 K (i-e        150° C.);    -   t(eq) is expressed in hours;    -   15683 is a temperature derived from the diffusion activation        energy of Mg, Q=130400 J/mol.

Aging step, particularly according to the preceding embodiments, isassumed to improve both AP and FSP resistance.

According to a preferred embodiment, the armor component provided is aplate having a final thickness ranging between 0.5 inch and 3 inches.

The alloy generally comprises, and in some instances consistsessentially of, zinc (Zn), copper (Cu) and magnesium (Mg) as mainalloying ingredients, with at least one dispersoid forming elements, thetotal content of dispersoid forming elements being at least 0.04 wt. %,and the remainder substantially including aluminum, incidental elements,and impurities.

The Zn content ranges between about 8.4 wt. % and about 10.5 wt. %,preferably between 8.5 wt. % and 9.5 wt. % and more preferably between8.5 wt. % to 9 wt. % Trials have shown that such content resulted in thehighest results in both AP and FSP ballistic tests and/or in animprovement of spall resistance score.

The magnesium content ranges between about 1.3 wt. % and about 2 wt. %,preferably between 1.5 wt. % to about 2 wt. %, and more preferably fromabout 1.6 wt. % to 1.9 wt. %. In a preferred embodiment, the Mg/Zn ratiois lower than or equal to 0.25, and preferably lower than or equal to0.20, where Mg and Zn denote weight percentages of magnesium and zincrespectively.

The copper content ranges between about 1.2 wt. % and about 2 wt. %.Preferably, Cu content lies between 1.5 wt. % and 1.9 wt. %. High AP andFSP resistances were obtained when copper and magnesium contents wereapproximately the same, i-e typically when 0.9≤Cu/Mg≤1.1.

At least one dispersoid forming element such as Zr, Sc, V, Hf, Ti, Crand Mn is added. As used herein, dispersoid forming elements meanselements that are deliberately added so as to control the grainstructure. The total content of dispersoid forming elements is at least0.04 wt. %, preferably from about 0.04 wt. % to about 0.3 wt. %. Theoptimum levels of dispersoid forming elements depend on the processing.When scandium is added, its content is preferably lower than about 0.3wt. %, and more preferably lower than 0.17 wt. %. When combined with Zr,the sum of Sc and Zr is preferably less than about 0.17 wt. %. The alloymay also include Cr, Hf and V, with content lower than 0.3 wt. %, andpreferably lower than 0.15 wt. %. When Mn is added, its content ispreferably less than 0.3 wt. %.

In a preferred embodiment, the dispersoid forming element is essentiallyzirconium. Preferably, Zr content is less than about 0.15 wt. %, morepreferably from 0.04 to 0.1 wt. %, and even more preferably from 0.05 to0.08 wt. %. The best AP and FSP resistance compromise and/or the highestspall resistance score is observed when 0.05 wt. %≤Zr≤0.08 wt. %. Theinventors have shown that, in comparison with the 7XXX alloy seriesdescribed in U.S. 61/948,870, lowering the Zr content as well asintroducing a cold working before SHT improved spall resistance andmaintained a high AP and FSP compromise so that

(i) V50 (FSP 20 mm)>1633 T²−1479 T+1290 where T is the thickness plate(unit: inch) and the unit of V50 is feet/s; and(ii) V50 (.30 cal AP M2)>−282 T²+1850 T+610 where T is the thicknessplate (unit: inch) and the unit of V50 is feet/s.

It is assumed that such Zr content, as well as performing a cold workingbefore SHT and quench, results in an increase of the grain size, as wellas more equiaxed grain shapes.

As used herein, impurities mean elements that may be found in the alloyin minor amounts, but that are not intentionally added to the alloy.Those elements result from natural impurities in the individual alloyelements or from the manufacturing process. Fe and Si are the mainimpurities generally present in aluminum alloys. Fe content ispreferably lower than 0.3 wt. %, and more preferably lower than 0.1 wt.%. Si content is preferably lower than 0.2 wt. %, and more preferablylower than 0.1 wt. %. Preferably, each other impurity element is presentat up to about 0.05 wt. % with a total impurity (other than Fe or Si)content up to about 0.15 wt. %, based upon the total weight of the alloytaken as wt. %.

As used herein, incidental elements mean elements that may be optionallyadded to the alloy during the manufacturing process. Addition of suchelements results from casting aids and deoxidizers. Titanium, Titaniumboride (TiB₂) or titanium carbide (TiC) are usual grain refiners.Deoxidizers may include Ca, Sr and Be. Preferably, the amount of theincidental elements Ca, Sr, Be, Br and C lies below 0.005 wt. %, that ofTi below 0.05 wt. %.

In a preferred embodiment, the alloy chemistry is:

-   -   8.5 wt. %≤Zn≤9.5 wt. %;    -   1.5 wt. %≤Mg≤2 wt. %;    -   1.5 wt. %≤Cu≤1.9 wt. %;    -   0.04 wt. %≤Zr≤0.10 wt. %, and preferably 0.05 wt. %≤Zr≤0.08 wt.        %;    -   up to 0.15 wt. % dispersoid forming element other than Zr;    -   the remainder substantially including aluminum, incidental        elements, and impurities.

Another aspect of the present invention is an armor component producedfrom a 7XXX series aluminum alloy consisting essentially of:

-   -   8.4 wt. %≤Zn≤10.5 wt. %;    -   1.3 wt. %≤Mg≤2 wt. %;    -   1.2 wt. %≤Cu≤2 wt. %;    -   at least one dispersoid forming elements, with a total content        of dispersoid forming elements of at least 0.04 wt. %;    -   the remainder substantially including aluminum, incidental        elements, and impurities;        wherein said 7xxx series aluminum alloy is cold worked with a        thickness reduction from 0.5 to 15% (as defined previously,        0.5≤x₁≤15) before a solution heat treatment and is in the form        of a plate having a final thickness of about 0.5 to about 3        inches so as to achieve an improved spall resistance compared to        an armor component obtained with the same manufacturing process        except that said manufacturing process does not comprise a cold        working step before the solution heat treatment.

EXAMPLES Example 1: Spall Resistance

Alloy plate products were made from alloys having the chemicalcompositions, in weight percent, shown in Table 1.

TABLE 1 composition of plate products (wt. %) Alloy Zn Cu Mg Zr Si Fe A9.06 1.85 1.82 0.10 0.01 0.03 B 8.97 1.85 1.85 0.07 0.04 0.07

Plate products were made using the following process:

-   -   casting an ingot of an alloy whose composition is indicated in        table 1; homogenizing the ingot;    -   hot working the homogenized ingot to arrive at an intermediate        gauge T₁;    -   for plate products B-3 and B-4 solely, cold working the ingot at        said intermediate gauge to arrive at a final gauge T₂, thereby        reducing the thickness of the ingot at said intermediate gauge        T₁ by respectively 2.9% and 6.3%;    -   solution heat treating the plate;    -   quenching;    -   for plate product A solely, stretching the plate to obtain a        plastic deformation of about 2%;    -   artificially aging the plate.

All sample plates were aged during a two-stage process. Sample A wasaged during 24 hours at 120° C. (1^(st) step) followed by 35 hours at150° C. (second step). Samples B-1, B-2, B-3 and B-4 were aged during 6hours at 120° C. (1^(st) step), followed by 16 hours at 160° C. (secondstep).

TABLE 2 experimental results Final Spall Velocity Plate gauge ColdResistance (FSP 20 product (inch) Working Score mm) ft/s A 1.37 No 5.353608 B-1 1.35 No 3 2318 B-2 1.35 No 3 2346 B-3 1.3 Yes 2.5 2299 x₁ = 2.9B-4 1.25 Yes 2 2279 x₁ = 6.3

The final thickness of each plate product ranges between 1.25 and 1.37inches. As can be noticed on the third column of Table 2, samples A, B-1and B-2 were not submitted to cold working before SHT, whereas coldrolling before SHT was performed on samples B-3 and B-4, therebyreducing the thickness of the so called intermediate sample platerespectively by 2.9% and 6.3%. Values given with respect to samples B-3and B-4, in the third column of table 2, represent the value x₁ suchthat T₂=T₁−(x₁*T₂)/100.

Samples B-3 and B-4 combine a low Zr content within a preferred range aswell as a cold working step before solution heat treatment and quench.

For all plate products, spall resistance was investigated with a FSPtest according to MIL-STD-662F (1997) standard. Trials were performedusing 20 mm FSP rounds which comply with MIL-DTL-46593B. The dimensionsof the FSP rounds are the following:

-   -   diameter: 20 mm-0.787 inch;    -   length: 23.0 mm-0.9 inch;    -   flat: 9.3 mm-0.366 inch.

The fourth column of table 2 shows the spall resistance score. Thisscore is determined by the following method. As shown on FIG. 1, on therear surface, surrounding the site of impact b, is an area of materialwhich was visibly affected by the ballistic strike and the partial orcomplete penetration by the FSP round into the plate. The boundary ofthis affected area is indicated on FIG. 1 with the dotted line a. Alongwith any possible exit hole of the FSP round, any material plug and areaof any delaminated material is included within the deformed area. Thearea also includes bulged or fractured material, which is stillconnected to the test plate. Radiating perpendicular from the directionof impact (i.e. along the rear surface) a length c is measured whichrepresents the longest distance from the site of impact to the edge orboundary of the deformed area. This maximum length c is than doubled andfrom the new value 20 mm is subtracted, which corresponds to thediameter of the FSP round. The remaining total is divided by 20 mm, soas to get a dimensionless parameter, so-called Spall Resistance Score.The spall resistance score is 0 when only a plug is formed, and nosignificant lateral material is affected by the impact. Higher scoresrepresent multiples of the impacting round diameter. A better score isas low as possible.

The fifth column of Table 2 shows the velocities of the projectile thatwere measured when performing FSP tests.

From these results, it can be concluded that

-   -   Plate products B-3 and B-4 exhibit a better spall resistance        than Plate products B-1 and B-2;    -   Plate product B-4 exhibits a better spall resistance than Plate        product B-3.

This tends to show that a cold working step before SHT results in animprovement of the spall resistance. Moreover, combining such coldworking together with a low amount of Zr might significantly improve thespall resistance score, while maintaining a high resistance with respectto both AP and FSP rounds, as will be assessed in example 2.

Example 2: AP and FSP Properties

Alloy plate products were made from alloys having the chemicalcompositions, in weight percent, shown in Table 3.

TABLE 3 composition of sample plates (wt. %) in example 2 Alloy Zn Cu MgZr Si Fe C 8.88 1.81 1.72 0.09 0.04 0.05 D 8.92 1.83 1.78 0.07 0.04 0.06E 8.85 1.63 1.61 0.06 0.04 0.06

Alloys C, D and E have a chemistry according to the invention.

Plate products were made using the following process according to theinvention:

-   -   casting an ingot of an alloy whose composition is indicated in        table 3;    -   homogenizing the ingot;    -   hot working the homogenized ingot to arrive at an intermediate        gauge T₁;    -   cold working the ingot at said intermediate gauge T₁ to arrive        at a final gauge T₂, thereby reducing the thickness of the        ingot, at said intermediate gauge T₁ by 2.9% (x₁=2.9);    -   solution heat treating the plate;    -   quenching;    -   stretching the plate to obtain a plastic deformation between 2%        to 3%;    -   artificially aging the stretched plate during 6 hours at 120°        C., followed by 16 hours at 160° C.

Plate products had different thicknesses varying from 1.0″ to 1.6″ andwere tested for their ballistic properties. Two ballistic tests havebeen carried out pursuant to U.S. military standard MIL-STD-662F (1997),namely the armor piercing test using 0.3 inch (7.62 mm) projectiles andthe FSP test using 20 mm fragment simulating projectiles. The AP and FSPresults are listed in Table 4 and compared to the minimum requiredballistic limits defined in US Military specification MIL-DTL 32375(respectively, V50 (0.3 Cal AP M2) 7085 requirement: MIL-DTL-32375 (MR)Appendix A, page 19-20, column “Required BL(P)—Type B” and V50 (FSP 20mm) 7085 requirement: MIL-DTL-32375 (MR) Appendix A, page 18, column“Required BL(P)—Type B”). This specification covers 7085 wroughtaluminum alloy armor plate for non-fusion welded applications in nominalthickness from 0.500 to 3.000 inch and defines minimum requiredballistic limits with respect to different kinds of projectiles as wellas plate thicknesses.

TABLE 4 experimental results of example 2 V50 (0.3 V50 (FSP cal AP M2)20 mm) % Final V50 (0.3 % greater V50 greater Plate gauge cal AP than7085 (FSP 20 than 7085 product (inch) M2) ft/s requirement mm) ft/srequirement C 1.11 2342 +2.23 1645 +3.98 D 1.61 3350 +11.93 E 1.00 2211+2.65 1506 +9.69

Plate products C, D and E have combined high AP and FSP performances. Inparticular, all the preceding plate products meet the minimum requiredballistic limits defined in US Military specification MIL-DTL 32375 foralloy 7085. Moreover, regarding examples 1 and 2 combining cold workingbefore SHT together with a low amount of Zr, namely Zr≤0.08 wt. %, seemsto significantly improve the spall resistance score, while maintaining ahigh resistance with respect to both AP and FSP rounds.

What is claimed is:
 1. A method of producing an armor component,comprising: a) casting a 7XXX series aluminum alloy to obtain an ingot,wherein said alloy comprises or consists essentially of 8.4 wt.%≤Zn≤10.5 wt. %; 1.3 wt. %≤Mg≤2 wt. %; 1.2 wt. %≤Cu≤2 wt. %; at leastone dispersoid forming element, with a total content of dispersoidforming elements of at least 0.04 wt. %; the remainder substantiallyincluding aluminum, incidental elements, and impurities; b) homogenizingsaid ingot; c) hot working said homogenized ingot to obtain a platehaving a first thickness T1; d) cold working the plate having the firstthickness to obtain a plate having a second thickness T2, whereinT2=T1−(x₁*T2)/100 and 0.5≤x₁≤15; e) solution heat treating; f)quenching; and g) aging.
 2. The method of claim 1, wherein 2≤x₁≤10,optionally 4≤x₁≤8.
 3. The method of claim 1, wherein d) is a coldrolling step.
 4. The method of claim 1, wherein g) includes at least atwo step aging.
 5. The method of claim 4, wherein said two-step agingincludes: a first aging of about 4-8 hours at about 110° C. to 130° C.;and a second aging of about 12-20 hours at about 130° C. to 180° C. 6.The method of claim 1, wherein g) is performed so that the totalequivalent time at 150° C. is between about 5 h to about 50 h,optionally about 10 h to about 50 h.
 7. The method of claim 1,including, between f) and g), another cold working to obtain a platehaving a third thickness T3.
 8. The method of claim 7, wherein said coldworking to obtain a plate having a third thickness T3 results in aplastic deformation ranging from 1% to 3%.
 9. The method of claim 7,wherein said cold working to obtain a plate having a third thickness T3comprises or consists of stretching.
 10. The method of claim 1,resulting in an armor component having a final thickness ranging between0.5 inch and 3 inches.
 11. The method of claim 1, wherein said 7XXXseries aluminum alloy comprises Zr as a dispersoid forming element,wherein 0.04 wt. %≤Zr≤0.15 wt. %.
 12. The method of claim 1, wherein0.04 wt. %≤Zr≤0.08 wt. %.
 13. An armor component produced from a 7XXXseries aluminum alloy comprising or consisting essentially of: 8.4 wt.%≤Zn≤10.5 wt. %; 1.3 wt. %≤Mg≤2 wt. %; 1.2 wt. %≤Cu≤2 wt. %; at leastone dispersoid forming element, with a total content of dispersoidforming elements of at least 0.04 wt. %; the remainder substantiallyincluding aluminum, incidental elements, and impurities; wherein said7xxx series aluminum alloy is in the form of a plate having a finalthickness of about 0.5 to about 3 inches and is manufactured by: a)casting said 7XXX series aluminum alloy to obtain an ingot, b)homogenizing said ingot; c) hot working said homogenized ingot to obtainan plate having a first thickness T1; d) cold working the plate havingthe first thickness to obtain a plate having a second thickness T2,wherein T2=T1−(x₁*T2)/100 and 0.5≤x₁≤15; e) solution heat treating; f)quenching; and g) aging; so as to achieve an improved spall resistancecompared to an armor component obtained with the same manufacturingprocess except that said manufacturing process does not comprise coldworking before the solution heat treatment.
 14. The armor component ofclaim 13, wherein said 7xxx series aluminum alloy comprises Zr as adispersoid forming element, and optionally wherein 0.04 wt. %≤Zr≤0.15wt. %.
 15. The armor component of claim 14, wherein 0.04 wt. %≤Zr≤0.08wt. %